Ube Industries, Inc.

Shunji Ohe

Toshihiro Inaike

Shuji Yamamoto

Kazunori Otsuka

An aromatic polyamic acid solution composition useful as an electrically insulating varnish, comprises (1) an aromatic polyamic acid which is a polymerization product of (A) a tetracarboxylic acid component containing at least 80 molar % of the sum of (a) a first acid ingredient consisting of 3,3',4,4'-biphenyltetracarboxylic dianhydride and (b) a second acid ingredient consisting of at least one member selected from the group consisting of pyromellitic dianhydride, and 3,3'4,4'-benzophenone tetracarboxylic dianhydride, the molar ratio of the first acid ingredient to the second acid ingredient being in the range of from 30:70 to 75:25, with (B) an amine component consisting of at least one aromatic amine in a molar ratio of the tetracarboxylic acid component to the amine component of from 97:100 to 103:100, and which polymeric acid has a logarithmic viscosity number of from 0.1 to 1.5 determined in a concentration of 0.5 g/100 ml in N-methyl-2-pyrrolidone at a temperature of 30.degree. C., and dissolved in a concentration of from 5% to 40% by weight in (2) an organic polar solvent.

Growing community of inventors

Ichihara, Japan

Shunji Ohe